The present invention relates generally to the field of waterless lithographic printing plates. More particularly, the present invention pertains to a media and fluid material set which comprise (a) a media with a support that bears a hydrophilic receiving surface; and, (b) a fluid material comprising a liquid carrier medium and a reactive component, which comprises a transition metal complex of a fluorinated organic acid. The reactive component reacts after application of the fluid material to the hydrophilic receiving surface to form an ink-releasing layer on the receiving surface. The present invention also pertains to waterless lithographic printing plates with such ink-releasing layers which are suitable for imaging by laser-induced thermal ablation and to imaged waterless lithographic printing plates with such ink-releasing layers, made by an ink jet printing application, by laser-induced thermal ablation, or by other imaging processes, and methods of making such waterless lithographic printing plates.
As printing plate technology has steadily evolved in recent years from analog imaging materials and methods to digital imaging materials and methods, a number of imaging techniques capable of use in digital printing have been described for use in computer-to-plate imaging systems. Examples of these digital printing technologies for computer-to-plate applications include laser printing, laser-induced thermal ablation imaging, and ink jet printing.
Throughout this application, various publications, patents, and published patent applications are referred to by an identifying citation. The disclosures of the publications, patents, and published patent applications referenced in this application are hereby incorporated by reference into the present disclosure to more fully describe the state of the art to which this invention pertains.
Exemplary of laser printing techniques for computer-to-plate applications is U.S. Pat. No. 5,304,443 to Figov. Examples of laser-induced thermal ablation techniques for computer-to-plate applications include U.S. Pat. Nos. 5,353,705 and 5,487,338 both to Lewis et al., and U.S. Pat. Nos. 5,605,780 and 5,691,114, both to Burberry et al. U.S. Pat. Nos. 4,003,312 to Gunther, U.S. Pat No. 4,833,486 to Zerillo, U.S. Pat No. 5,312,654 to Arimatsu, et al, U.S. Pat. No. 5,501,150 to Leenders et al., U.S. Pat. Nos. 5,738,013 and 5,849,066, both to Kellett, Japanese Kokai 62-25081 to Katagiri et al., and EP 776,763A1 to Hallman et al. are examples of ink jet printing techniques suitable for computer-to-plate applications.
Lithographic printing has long been a widely used printing technique. By the term xe2x80x9clithographic,xe2x80x9d as used herein, is meant to include various terms used synonymously, such as offset, offset lithographic, planographic, and others. Much effort has been directed at developing computer-to-plate imaging techniques for providing lithographic printing plates. These efforts have been made for both of the main types of lithographic printing plates: wet lithographic printing plates and dry or waterless printing plates.
By the term xe2x80x9cwet lithographic,xe2x80x9d as used herein, is meant the type of lithographic printing plate where the inking or image areas of the plate that receive the printing ink from the ink roller and then transfer this ink to the receiving media, such as a type of paper, are ink-receptive or oleophilic and where the non-inking or background areas of the plate that do not accept printing ink from the ink roller and thus do not transfer any ink to the receiving media are hydrophilic and receive an aqueous fountain solution during the printing process before contact with the ink roller. This aqueous or xe2x80x9cwetxe2x80x9d layer in the non-inking areas renders these areas ink repellent or oleophobic to the printing ink.
By the terms xe2x80x9cdry lithographicxe2x80x9d or xe2x80x9cwaterless lithographic,xe2x80x9d as used herein, is meant the type of lithographic printing plate where the inking or image areas of the plate that receive the printing ink from the ink roller and then transfer this ink to the receiving media are ink-receptive and where the non-inking or background areas of the plate that do not accept printing ink from the ink roller and thus do not transfer any ink to the receiving media are ink-releasing in a xe2x80x9cdryxe2x80x9d or xe2x80x9cwaterlessxe2x80x9d state and do not utilize a xe2x80x9cwetxe2x80x9d solution of any type, such as an aqueous fountain or dampening solution, to render the non-inking areas repellent to the printing ink. Thus, the dry or waterless lithographic printing process has an advantage over the wet lithographic printing process in that the operator does not have the additional variable of an aqueous fountain solution to identify as suitable for the specific printing operation and then to have to maintain during the course of the printing operation. This advantage from simpler equipment, processing, and printing solution and other setup requirements is particularly useful in computer-to-plate lithographic printing where a fast setup and turnaround time for the printing run is highly desirable to achieve the overall printing speed and convenience possible from computer-to-plate based printing systems.
For waterless lithographic printing, the ink-releasing material in non-inking areas of the plate is typically a material of low surface energy, such as surface tension below about 20 dynes/cm, which makes the layer abhesive or repellent to the oil-based waterless printing inks as well as to aqueous dampening solutions. To provide this low surface energy, elastomeric silicone polymer materials are commonly used for waterless lithographic printing plates, as for example, described in U.S. Pat. No. 4,259,905 to Abiko et al., U.S. Pat. No. 5,017,457 to Herrman et al., and U.S. Pat. No. 5,212,048 to Lewis et al. Computer-to-plate printing for use in waterless lithographic printing is known, as, for example, described in U.S. Pat. Nos. 5,310,869, 5,339,737, 5,540,150 and 5,551,341, all to Lewis et al., for laser-induced thermal ablation and in U.S. Pat. No. 4,003,312 to Gunther for ink jet printing. Some disadvantages of silicone materials for waterless lithographic plates include poor adhesion of the silicone-containing layer to support materials, such as aluminum plates, and soft and elastomeric properties which may interfere with the durability needed for long press runs, such as over 50,000 impressions, and which may not cleanly release the elastomeric and somewhat tacky waterless printing inks to provide high resolution and consistent image quality. To overcome the intrinsic abhesive properties of the silicone materials, one or more additional layers have been utilized to improve the adhesion to the support material. Thus, it would be desirable to have a tough, durable material with good adhesion to the support material and with excellent ink-releasing properties for use in various computer-to-plate systems to prepare waterless lithographic plates, particularly those capable of long production runs of 50,000 impressions and more with a consistent image quality.
As an alternative to silicone materials as the low surface energy materials for the ink-releasing areas in waterless lithographic plates, fluorinated materials have been reported, such as, for example, in U.S. Pat. No. 3,859,090 to Yoerger et al., which describes a fluorinated acrylate polymer with a fluorinated or silicone oil in an ink repellent composition for waterless plates.
An ink-releasing material, which is applicable for waterless lithographic printing plates and provides a tough, durable layer with excellent ink-releasing properties, and which may be utilized in computer-to-plate imaging processes, such as laser-induced thermal ablation and ink jet printing, would be of great value to the printing industry.
One aspect of the present invention pertains to a media/fluid material set for use in preparing a waterless lithographic printing plate, which media/fluid material set comprises (a) a media comprising a support that bears a hydrophilic receiving surface; and, (b) a fluid material comprising a liquid carrier medium and a transition metal complex of a fluorinated organic acid, wherein the complex reacts after application of the fluid material on the hydrophilic receiving surface and thereby forms an ink-releasing layer on the receiving surface. In a preferred embodiment, the reactive complex of this invention comprises a chromium complex of a fluorinated organic acid, and more preferably, a Werner complex of trivalent chromium and a fluorinated organic acid. In a most preferred embodiment, the fluorinated organic carboxylic acid of the Werner complex of the media/fluid material set of this invention is selected from the group consisting of non-cyclic and cyclic carboxylic acids having 4 to 18 carbon atoms.
In one embodiment, the fluid material of the present invention is an ink jet fluid marking material, and the application method utilized for the fluid material is an ink jet printing application, and preferably, the ink jet printing application is in a desired imagewise pattern, thereby forming an ink-releasing layer in the desired imagewise pattern on the hydrophilic surface of the support.
In one embodiment, the hydrophilic receiving surface of the media of this invention further comprises a catalyst to increase the rate of reaction, and preferably, the catalyst is an alkaline material.
In one embodiment, the hydrophilic receiving surface of the media of the present invention comprises a hydrophilic material selected from the group consisting of: polyvinyl alcohol and copolymers thereof; cellulosic polymers; polyacrylates and copolymers thereof; polymethacrylates and copolymers thereof; polymaleic anhydrides and derivatives and copolymers thereof; polyvinyl pyrrolidones and copolymers thereof; quaternary ammonium polymers and copolymers thereof; polyamides; and aluminum oxides, and preferably, the aluminum oxides are selected from the group consisting of: aluminum boehmites; gamma-aluminum oxides; alpha-aluminum oxides; aluminum oxides formed by the oxidation of aluminum metal by oxygen; and aluminum oxides formed by an anodization process.
In a preferred embodiment, the transition metal complex of the fluid material of the present invention reacts upon exposure to heat after application of the fluid material on the hydrophilic receiving surface, and most preferably, the complex reacts with the hydrophilic receiving surface.
In one embodiment, the support of the media of the present invention is a paper. In one embodiment, the support of the media of this invention is a polymeric plastic film. In one embodiment, the support of the media of the present invention is aluminum.
One aspect of the present invention pertains to an ink-releasing plate for preparing a waterless lithographic printing plate, which plate comprises (a) a support that bears a hydrophilic surface; and, (b) an ink-releasing layer overlying the hydrophilic surface of the support, wherein the ink-releasing layer comprises a reaction product of a transition metal complex of a fluorinated organic acid. In one embodiment, the ink-releasing layer further is capable of being imaged using laser-induced thermal ablation, wherein the ablation removes the ink-releasing layer in exposed regions thereof to thereby reveal the hydrophilic surface of the support. In a preferred embodiment of the ink-releasing plates of this invention, the transition metal complex is a chromium complex, and more preferably, the complex comprises a Werner complex of trivalent chromium and a fluorinated organic carboxylic acid. In a most preferred embodiment, the fluorinated organic carboxylic acid of the Werner complex of the ink-releasing plates of this invention is selected from the group consisting of non-cyclic and cyclic carboxylic acids having 4 to 18 carbon atoms.
In one embodiment, the ink-releasing layer of the ink-releasing plates of this invention further comprises a sensitizer to increase the rate of imaging by laser-induced thermal ablation, and preferably, the sensitizer is an infrared-absorbing material.
One aspect of the present invention pertains to an imaged waterless lithographic printing plate comprising (a) a support that bears a hydrophilic surface in the ink-receiving areas of the support; and, (b) an ink-releasing layer in a desired imagewise pattern overlying the hydrophilic surface of the support, wherein the ink-releasing layer comprises a reaction product of a transition metal complex of a fluorinated organic acid. In a preferred embodiment of the imaged waterless lithographic plates of the present invention, the transition metal complex is a chromium complex, and more preferably, the chromium complex comprises a Werner complex of trivalent chromium and a fluorinated organic carboxylic acid. In a most preferred embodiment, the fluorinated organic carboxylic acid of the Werner complex of the imaged plates of this invention is selected from the group consisting of noncyclic and cyclic carboxylic acids having 4 to 18 carbon atoms.
In one embodiment of the imaged waterless lithographic plates of this invention, the hydrophilic surface in the ink-receiving areas of the support comprises a hydrophilic material selected from the group consisting of: polyvinyl alcohol and copolymers thereof; cellulosic polymers; polyacrylates and copolymers thereof; polymethacrylates and copolymers thereof; polymaleic anhydrides and derivatives and copolymers thereof, polyvinyl pyrrolidones and copolymers thereof; quaternary ammonium polymers and copolymers thereof; polyamides; and aluminum oxides; and preferably, the aluminum oxides are selected from the group consisting of: aluminum boehmites; gamma-aluminum oxides; alpha-aluminum oxides; aluminum oxides formed by the oxidation of aluminum metal by oxygen; and aluminum oxides formed by an anodization process. In a most preferred embodiment, the reaction product in the ink-releasing layer comprises a reaction product of the transition metal complex of a fluorinated organic acid with the hydrophilic surface of the support.
In one embodiment, the support of the imaged plates of the present invention is a paper. In one embodiment, the support of the imaged plates of this invention is a polymeric plastic film. In one embodiment, the support of the imaged plates of the present invention is aluminum.
One aspect of the present invention pertains to a method of preparing an ink-releasing plate for use in preparing a waterless lithographic printing plate, which method comprises the steps of (a) providing a support that bears a hydrophilic receiving surface; (b) applying a fluid material comprising a liquid carrier medium and a transition metal complex of a fluorinated organic acid to the hydrophilic receiving surface; (c) removing the liquid carrier medium; and (d) reacting the transition metal complex, thereby forming an ink-releasing layer on the receiving surface. In a preferred embodiment, the transition metal complex reacts in step (d) upon exposure to heat, and most preferably, the transition metal complex reacts in step (d) with the hydrophilic receiving surface. In a preferred embodiment of the method of preparing an ink-releasing plate of this invention, the transition metal complex is a chromium complex of a fluorinated organic acid, and more preferably, the chromium complex comprises a Werner complex of trivalent chromium and a fluorinated organic carboxylic acid. In a most preferred embodiment of the method of preparing an ink-releasing plate of this invention, the fluorinated organic carboxylic acid of the Werner complex is selected from the group consisting of non-cyclic and cyclic carboxylic acids having 4 to 18 carbon atoms.
In one embodiment of the method of preparing an ink-releasing plate of the present invention, the fluid material is an ink jet fluid marking material and the application of the fluid material to the hydrophilic receiving surface is carried out by an ink jet printing application.
One aspect of the present invention pertains to methods of preparing an imaged waterless lithographic printing plate, comprising providing a lithographic plate blank having a support that bears a hydrophilic receiving surface and forming an image on the hydrophilic receiving surface of the support with an ink jet printer in an ink jet printing application, wherein an ink jet fluid marking material utilized in the ink jet printer comprises a liquid carrier medium and a reactive component, which reactive component comprises a transition metal complex of a fluorinated organic acid. The transition metal complex reacts upon exposure to an energy source after the ink jet printing application, thereby forming an effective amount of an ink-releasing layer in a desired pattern on the support. In a preferred embodiment of the methods of preparing imaged waterless plates of this invention, the transition metal complex is a chromium complex of a fluorinated organic acid, and more preferably, the chromium complex comprises a Werner complex of trivalent chromium and a fluorinated organic carboxylic acid. In a most preferred embodiment of the methods of preparing imaged waterless plates of the present invention, the fluorinated organic carboxylic acid is selected from the group consisting of non-cyclic and cyclic carboxylic acids having 4 to 18 carbon atoms.
In one embodiment of the methods of making imaged waterless lithographic plates of the present invention, the ink jet printing application is done in a desired imagewise pattern and the ink-releasing layer is formed in a desired imagewise pattern on the support. In a preferred embodiment, the energy source is heat, and most preferably, the transition metal complex reacts with the hydrophilic receiving surface. In one embodiment, the support is a paper. In one embodiment, the support is a polymeric plastic film. In one embodiment, the support is aluminum.
One aspect of the present invention pertains to a method for preparing an imaged waterless lithographic printing plate, which method comprises the steps of (a) providing a support that bears a hydrophilic receiving surface; (b) applying a fluid material comprising a liquid carrier medium and a reactive component to the receiving surface, wherein the reactive component comprises a transition metal complex of a fluorinated organic acid; (c) removing the liquid carrier medium; (d) reacting the reactive component, thereby forming an ink-releasing layer on the receiving surface; and, (e) exposing the ink-releasing layer to laser-induced thermal ablation in a desired imagewise pattern, thereby removing the ink-releasing layer in the exposed regions thereof to thereby reveal the hydrophilic surface of the support in the desired imagewise pattern.
As one of skill in the art will appreciate, features of one embodiment and aspect of the invention are applicable to other embodiments and aspects of the invention.